50 



MEXICO, CENTRAL AMERICA, WEST INDIES. 



But although in some exceptional districts the zones are brought into sharp 

 juxtaposition, they merge almost everywhere by successive transitions one into 

 another. It is only in a very general way that any given region can be said to 

 belong to such or such a zone, and the parting line oscillates greatly, especially 

 about the base of the mountains. A zone of mutual overlapping has been 

 developed under the thousand modifjing conditions of soil, temperature, winds, 

 the struggle for existence between the various species of plants. Certain glens 

 and slopes even occur, which, in their vegetation, form tropical enclaves in the 

 very midst of the temperate zone. 



Regarded as a whole, Mexico, which is intersected by the tropic of Cancer 



Fig. 24. — Veetical Disposition of the Mexican Climates. 

 Sen le 1 : 12,000,000. 



102°40 West oF GreenwicK 97°4o 



Warm. 



Temperate. 



Cold. 

 310 Miles. 



almost exactly in the centre, is a hot countr}^ Assuming its mean elevation to be 

 3,600 feet, the average temperature of these latitudes would be about 60 F., or 

 nearly the same as that of Nice or Perpignan in the south of France, but far below 

 that of African regions, such as the Sahara and Nubia, lying under the same parallels. 



The Anahuac plateau may be described as a temperate region upheaved 

 above the tropical zone. It corresponds to the temperate and cold regions of 

 Abyssinia, which also dominate "hot lands," such as Massawah and the Danakil 

 territory. But however favoured the Abyssinian plateau may be in its climate, 

 it is vastly inferior to Mexico in the advantages of position and means of access. 



In its latitude, Mexico lies well within the zone of the trade winds, which 

 blow regularlv from north-east to south-west, or from east to west, on the shores 



